DETERGENT-ENHANCED DISSOCIATION OF ENDOGENOUS PEPTIDES FROM PI-DRB1-ASTERISK-0401

A variety of detergents have been shown to catalyze the dissociation o f bound peptides from a soluble from of DRB10401. By using a class II molecule lacking the hydrophobic transmembrane region, the need for s olubilizing the transmembrane protein was removed and enabled the spec ific interaction between the class II protein and the amphiphile to be identified. The presence of detergent increased the rate of associati on of added peptide and the percent occupancy of the receptor, presuma bly because the dissociation of endogenous peptide was the rate-limiti ng step in binding. The data help explain the differences reported bet ween peptide binding to class II proteins on the surface of cells and binding to class II proteins solubilized in detergent. The interaction did not correlate with the critical micellar concentration of the det ergent nor were all amphiphilic structures equally effective, consiste nt with a specific interaction between the amphiphile and the MHC clas s II protein. Of the eight detergents examined, octyl glucoside was th e most efficient. These experiments did not distinguish between an all osteric mechanism or direct competition with the peptide for binding.